The present invention relates to a mounting substrate on which electronic parts are to be mounted, and which includes a base substrate having a usable substrate region used as part of electronic equipment to be manufactured and an unusable mounting region to be discarded.
A known mounting substrate on which electronic parts are to be mounted includes, as shown in FIG. 1, a base substrate 22 having a usable substrate region A used as part of electronic equipment to be manufactured and an unusable substrate region B to be discarded at the subsequent step.
The process of mounting electronic parts on such a mounting substrate 21 includes a dipping step for soldering the electronic parts on the base substrate 22 by a dip soldering method. Prior to this step, V-shaped grooves 23 are formed on a soldering surface side, on which solder is stuck at the dipping step, of the base substrate 22 by sawing. The grooves 23 are used for easily separating the base substrate 22 into the usable substrate region A and the unusable substrate region B by cleaving the base substrate 22 along the grooves 23.
For example, as shown in FIG. 1, in the case where the usable substrate region A having an approximately rectangular shape is formed at an approximately central portion of the base substrate 22 having an approximately rectangular shape, and the remaining peripheral portion is taken as the unusable substrate region B, two grooves 23a and 23b extending along a pair of the transverse sides of the base substrate 22 and two grooves 23c and 23d extending along a pair of longitudinal sides of the base substrate 22 are formed as the grooves 23. In this case, areas surrounded by the transverse sides of the base substrate 22 and the grooves 23a and 23b extending in parallel to the transverse sides are taken as a first unusable substrate region B1, and areas surrounded by the longitudinal sides of the base substrate 22 and the grooves 23c and 23d extending in parallel to the longitudinal sides and not crossing the first unusable substrate region B1 are taken as a second unusable substrate region B2.
Conduction state checking lands (hereinafter, referred to as simply as xe2x80x9clandsxe2x80x9d) 24 for checking, on the basis of the conducting state, whether or not the grooves 23 are certainly formed, are formed in the first unusable substrate region B1 and the unusable substrate region B2 on the soldering surface side of the base substrate 22 in which the grooves 23 are formed.
To be more specific, pairs of the lands 24 are formed such that each pair of the lands 24 are arranged on both sides of each groove 23 and are electrically connected to each other by means of a straight wiring pattern crossing the groove 23. Accordingly, in the example shown in FIG. 1, four pairs of the lands 24 corresponding to the four grooves 23a to 23d are provided.
The above-described mounting substrate 21, in which the lands 24 and the wiring patterns 25 are provided on the soldering surface side of the base substrate 22 and the grooves 23 are formed in the base substrate 22, is gradually moved, for example, in the direction shown by a hollow arrow C in FIG. 1, that is, from one end side to the other end side of the base substrate 22 in the transverse direction or from the other end side to the one end side of the base substrate 22 in the transverse direction, to be floated in a solder bath, whereby the soldering surface is brought in contact with solder and the solder is stuck on a specific soldering portion At this soldering step, for example, the entire first unusable substrate region B1 is supported by rail-like supporting claws provided in parallel to the soldering direction (shown by the arrow C), with a result that the entire first unusable substrate region B1 is taken as a non-contact portion, which is not brought into contact with solder.
As described above, for the related art mounting substrate 21 shown in FIG. 1, in the case of sticking solder on the soldering surface side, the entire first unusable substrate region B1 is taken as the non-contact portion against solder because it is supported by the supporting claws. In other words, the second unusable substrate region B2 and the usable substrate region A of the base substrate 22 are brought into contact with solder.
On the other hand, the conduction state checking lands 24 are member necessary for manufacture, which are useful only for checking the conduction state in the manufacturing process, and in order to ensure the conduction of the lands 24 prior to formation of the grooves 23 performed before soldering treatment, an insulating film, typically a resist film, is removed from the surface of each of the lands 24. As a result, upon soldering treatment, the lands 24 are in a state having a wettability against solder.
Such lands 24 are arranged on both the sides of each groove 23, and accordingly, for example, in the case of a pair of the lands 24 corresponding to one groove 23 extending in parallel to the transverse side, one of the lands 24 is arranged in the second unusable substrate region B2, which is brought into contact with solder. As a result, solder is stuck on the lands 24 in the second unusable substrate region B2 upon soldering treatment.
Most of solder materials are composed of noxious tin-lead based metals. Accordingly, if it is intended to separate the first and second unusable substrate regions B1 and B2 from the base substrate 22 at the subsequent step and to discard them, they become wastes containing noxious materials which exert adverse effect on global environments. Also since solder is stuck even on portions not required to be soldered, such as the conduction state checking lands 24, the usage of solder becomes large, thereby causing an inconvenience in raising the manufacturing cost of electric equipment manufactured by using the mounting substrate 21.
For the related art mounting substrate 21, in addition to the conduction state checking lands 24, necessary members for manufacture, such as other lands necessary only for manufacture and alignment marks are provided generally in the unusable substrate region B on the soldering surface side of the base substrate 22. If these members are arranged in the second unusable substrate region B2 and are in a state having a wettability against solder upon solder treatment because of removal of the resist films from the surfaces of the members, solder is stuck on the members like the conduction state checking lands 24. As a result, problems occur upon discarding the unusable substrate B1, as it becomes a noxious containing waste, and the usage of solder becomes large.
To provide a mounting substrate including a base substrate having a usable substrate region and an unusable substrate region, and also including on-substrate members, characterized in that even if solder is stuck on the on-substrate members, any noxious material containing waste does not occur when the unusable substrate region is separated from the usable substrate region and is discarded.
To achieve the above object, according to the present invention, there is provided a mounting substrate including: a base substrate having a usable substrate region used as part of a product and an unusable substrate region to be discarded, the base substrate being subjected to soldering treatment in which the surface thereof is brought into contact with solder; and on-substrate members arranged on a soldering surface side, to be subjected to the soldering treatment, of the base substrate, the on-substrate members being in a state in which the surfaces have a wettability against solder upon soldering treatment, wherein the on-substrate members are arranged in a non-contact portion with solder upon solder treatment in the unusable substrate region, in the usable substrate region, or in the non-contact portion and the usable substrate region.
In the case where the on-substrate members are arranged in the non-contact portion with solder upon soldering treatment in the unusable substrate region, even if the surfaces of the on-substrate members are in a state having a wettability against solder upon soldering treatment, solder is not stuck on the on-substrate members. In the case where the on-substrate members are arranged in the usable substrate region, even if solder is stuck on the on-substrate members, since the usable substrate region is not discarded, any noxious material containing material does not occur when the unusable substrate region is discarded. As a result, according to the mounting substrate of the present invention in which the on-substrate members are arranged in the non-contact portion with solder in the unusable substrate region, in the usable substrate region, or in the non-contact portion or the usable substrate region, it is possible to prevent occurrence of a noxious material containing waste when the unusable substrate region is discarded. Further, solder is not stuck on the on-substrate members arranged in the non-contact portion, the usage of solder upon soldering treatment can be reduced. Accordingly, it is possible to reduce the material cost, and hence to reduce the manufacturing cost of electronic equipment using the mounting substrate.